Tungsten Carbide Brotherhood Band Red Line Fire Fighter Ring Designed for Fire Fighters and their families as a symbol of the Brotherhood and bond in Fire Protection. Virtually indestructible: Tungsten Carbide is harder than tool steel and used in industrial applications such as drilling, cutting, and mining. Tungsten Carbide is considered a hypoallergenic metal. The rings contain NO Cobalt, which can irritate skin. Brotherhood Bands use only Nickel as a binder. Due to their hardness, Tungsten Carbide rings are almost impossible to re-size or engrave. Please be careful to order the correct size ring. Brotherhood Bands are covered by a Lifetime Warranty against breakage. Exchanges are also allowed if size becomes an issue.